dunno if it has been done before but im sure its possible. The only problem is the enclosure space behind the wall. If its to small you'll get reverbiration through your rear seats and that wont sound good.
10 inches would be small yet good for bass. Alpines require the least amount of enclosure space out of the common market subs, type r's are the cheapest i think but all alpines are pricy... the amp can probably fit in the back too if you manage to move a few things around
im assuming you want to put the subs in your rear wall (in boot). I think there are a few threads on the subject, do a search. I remember reading about some somewhere
this is seriously interesting, if you could get R34 GTR's for 30k and ship them to aus and register them that is a very good price... how much do R33 GTR's go for over there?
definetly, if i was currently looking for an R33, the second example i showed you is an excellent example. Good condition and good price considering the mods. Most cars from japan have some sort of minor damage but you need to remember that some of these cars are over 10 years old
heres a nice S2: http://www.prestigemotorsport.com.au/au/st...sp?StockID=2509
But this one i really like: http://www.prestigemotorsport.com.au/au/st...sp?StockID=2520
$22,000 will get you a fine example, there was this madd S2 for sale for $18,000, unfortunetly it was sold. dont worry, jspec can find you the right car in no time